Locomotive valve gear



LocouoTIvE VALVE: GEAR' Filed Feb. 24,. y1925 oo? v *an* *i l o 'n.p J m i9 v O gv j' o l I m... Illu CQ g, l D

` lNvz'NToR JG.DUNN

ATTORNEY 3. r. ma i 013@ atented 1%,

JAMES G. DUNN, OF MIMICO, ONTARIOQCANADA.

LOCGMOTIVE VALVE GEAR,

Application filed February rllhis invention relates to new and useful improvements in valve gears for locomotives and other types ot steam engines and is particularly related to valve gears ot the well known llalschaert type, and the object ot the invention is to provide a simple and highly etlicient arrangement of valve control mechanism which will allow a longer Vtravel without objectionable angular movement to any of the working parts when compared with valves ot the Tvllalschaerttype in use on locomotives at the present time.

Another object is'to provide a device of the class stated in whichthe valve movement will be always in advance oit and greater than the radius rod movement.

In my invention the constructiontlv briefly described, is very similar tothe standard lllalschaert vgear in that I employ the return crank principle for operating the links, the lap and lead movement being operated from the cross-head through connecting member known as the transmission lever or lap and lead lever. 1n my construction this transmission lever is connected to the crosshead by a union link and crosshead arm. The transmission lever extends upwardly and is forked just below the valvev stem which is positioned below the transmission lever trunnions which are placed in line with the reversinglink trunnion.. The transmission lever extends a short distance above its trunnions and pivotally mounted between the forked portions and depending from the upper end thereof is the combination lever which is connected to the front end ot the radius rod at a point radially coincident with the centre ot the transmission lever trunnions. rlhe end ot the combination lever is connected t-o the valve stein by means or" the valve stem link. Y

This construction ot transmission lever and combination lever increases the valve travel from 85% @40% Without increasing the swing ot the link when compared with the standard lalschaert gear.

ln the drawings:

Figure 1 is a side elevation otmy improved valve mechanism applied to a klocomotive. 4

Figure 2 is an end elevation showing the construction ot the transmission lever and combination lever.

Referring more particularly to the drawings which show part of the side of a locomotive, 11 designates the locomotive trame,

2li, 1925. -Serial N10. 11,263.

12 the main cylinders and 13 the valve or steam chest. The piston rod 14'is provided with a crosshead 15 which is pivotally con* qnected to a crank 16 on the driving wheel 17 by means ot'the connecting rod 18. The eccentric crank 19 is located 90o behind or in front 'of the main crank and is pivotally connected to onevend. 2O ot the reversing link 21 by means of the eccentric `rod 22. The reversing link is pivotally attached to the trame by means ot the bracket 23a in such a manner that the link block 23 which is slidably mounted in the slot 22 formed in the reversing link can be moved an even distance on each side oi" the centre of the bracket. The link block may be raised or lowered by means of the reversing lever 24 which is connected to the Vblock by means of the links 25 the rocker armr 26 and the link 85. .Depending from the crosshead is the crossheadV arm 27 which is connected Vto the lower end 28 of the transmission lever 29 by means of the link 30. Said lever 29 is pivotally mounted in trunnions 31 rotatably mounted in brackets 32 secured to the frame. The centre of the trunnions are in line with the centrev oi the link pivot and are spaced from one anotaer a distance equal to the lengthA of the radius rod 33 so that when the link block is in the centre position there is no movement in the radius rod and therefore no movement in the valve. stem 34- which is vconnected in the manner hereinafter described. The foregoing description has reference to the parts used in the standard Walschaert gearand the following description relates to the portion of the valve control mechanism in which my improved construction lies. Thetransmission link is forked just 'below the level of the valve stem, said torkedportion extending above the trunnions 31 where the upper ends 36 of thev forked vportion. may be brought together as shown for illustrative purposes. Pivotally suspended on ,a pin 37 passing through the ends 36 and between the fork is the combination lever 38, the lower end of which is connected to the valve stem link 39 which is connected to the valve stem. The connection between the combination lever and the valve stem is positioned preferably a short distance below the centre of the trunnions 31. The end 40 of the radius rod is connected to the combination lever at a point radially coincident with the centre of the truniiions 31y ot the transmission lever. Modifications may be made without departing from the spirit of the invention. In operation the back and forth movement of the bottom of the transmission link with the crosshead and pistonnimparts a radial movement to the top of the transmission lever (said radial movement being about the trunnions 31) and, consequently, an indirect movement to the top of the inverted combination lever which, using the radius rod as a fulcrum, imparts to thevalve rod and, therefore, to the valve a movement in the same direction as the piston, said movement being equal to the lap plus lead. The radius rod movement from the reversing link acting on the combination lever-Vat a point above the valve stem, imparts to the valve a movement always in advance and greater than the radius rod movement its-elf, because at the same time the top connection of the combination lever acts as a ulcrum andpermits the lower connection to swing between the forked end of the transmission link, imparting to the valve a travel in the opposite direction to the piston and crosshead. The combination lever being inverted, and the radius rod being connected to the combination lever above the valve stem connection and between the transmission lever tulcrmn points, enables this gear to increase the valve travel without increasing thefswing of the reversing link.

Having thus described my invention, what I claim is 1. In a valveY gear for locomotives and other types of steam engines, an .inverted combination lever connected at its lower end to the valve stem, a radius rodconnected to the combination lever above the valve stem connection, pivotally mounted means operated by the movement of the piston and connected to the upper end of the 4combination lever adapted to impart to the valve a predetermined movement in the same direction as the piston, kusing the radius -rod connection asa pivot, and means operable by the piston for moving the radius rod.

2. Ina valve geary for a steam engine, a lap and lead lever pivotally'mounted on the engine frame, means forwconnecting, the lower end of the lever to the .engine crosshead, a combination lever depending fromV the other endof the :lap and lead lever and a valve stemconnected to the combination lever at a point below the lap and lead lever pivot.

Ina valve gear for la steam engine, a fork ended lap and lead lever pivotally mounted on trunnions rotatably attached to the engine frame, a link connection between the lower end of -thevsaid lever and the cross-V mounted on trunnions secured to the engine frame, a link attachment betweenthe lower end of said lever and the crosshead `of the engine, a combination lever pivotally attached to the upper end of the lap and lead lever and depending between the arms of the forked end of same, a valve stem connected to th-e combination lever at a point below'` the level Aof the trunnions, a radius rod connected at one end to the combination lever at a point radially coincident with the trunnion centres, a slotted reversing linkpivotally attached to the frame, a link block slidably mounted in the reversing link and pivotally attached to the other end of the radius rod, means operable by the engine piston for operating thereversing link and means torv moving the link block to anyA desired position in the slot of the reversing link,

5. In a Valve gear for locomotives having cylinder valve chests, pistons, crossheads, driving wheels and connecting rods between the driving wheelsV and crossheads, a fork ended lap and lead lever pivotally mounted on trunnions secured 4to thel engine frame, said fork end being adapted to extend above the trunnions, a link connection between the crosshead and the lower end of the lap and lead lever, la combination lever rotatably suspended from the other end of the lap and lead lever and between the arms of the forked end thereof, a valve stem connected by link to the combination lever below the level of the trunnions, a slotted reversing link pivotally mounted on the frame, an Ieccentric rod connected to the .driving wheel and the reversing link, a link blockoslidably mounted in the slot, aradius rod having one endconnected to the link block and `the other end to the combination lever at aipoint radially coincident with the trunnions, and means for shitting the link block to any desired position in the slot.,

In witness whereof,A I have hereuntoset,

my hand. .Y

JAMES GVDUNN. 

